What Causes Blood Clots In The Vagina?

hi im 25 years old and have been on the pill since 16...i messed up my pills after my last period, so i havent taken them for about 3-4 weeks...i went to use the bathroom today and was trying to poop..instead, i noticed a blood clot come out of my vagina and now im bleeding like i would if i were on my period...wondering if this happened cause of my mix up with my pills?